Hydraulic motor having a hydraulic lock control drive pin

ABSTRACT

A radial piston hydraulic motor in which a valve, rotatably driven by the motor output, through a drive pin, provides timed fluid flow to and from the motor cylinders relative to rotation of the motor output. If the valve should seize in the cylinder housing, the pin will shear, opening a passage therein, to provide a fluid flow connection between the high pressure side of the motor and the motor case to prevent a hydraulic lock from forming in the cylinders.

United States Patent Dzioba 1 July 23, 1974 [54] HYDRAULIC MOTOR HAVINGA 3,730,054 5/1973 Dickinson 91 491 HYDRAULIC LOCK CONTROL DRIVE PINFOREIGN PATENTS OR APPLICATIONS Inventor: Donald Dzioba, Bridgeport,Mich- 198,258 8/1967 U S.S.R 91/491 [73] Assignee: General MotorsCorporation,

Detroit Mich. Primary ExammerW1l1|am L. Freeh Attorney, Agent, orFirmDonald F. Scherer [22] F11ed: Aug. 22, 1973' [21] Appl. No.: 390,386[57] ABSTRACT A radial piston hydraulic motor in which a valve, ro- 5211.5. c1. 91/491, 180/66 F, 91/180 tatably driven by the motor Output,through a drive [51 Int. Cl F0lb 13/06 P Provides timed fluid flow t0and from the motor [58] Field of Search 417/319; 180/66 F; 91/180,cylinders relative to rotation of the motor output. If 9 49 1 5 thevalve should seize in the cylinder housing, the pin will shear, openinga passage therein, to provide a 5 References Cited fluid flow connectionbetween the high pressure side UNITED STATES PATENTS of the motor andthe motor case to prevent a hydraulic lock from forming in thecylinders. 3,092,086 6/1963 Bata1lle 91/481 3,354,786 11/1967 Bedford91/180 2 Claims, 2 Drawing Figures Radial piston hydraulic motors aregenerally of two basic types. One type using a stationary housing with arotatable output shaft, and the other type using a stationary spindlewith a rotatable housing. The present invention is concerned with thelatter. ln radial piston motors having a stationary spindle and arotatable housing, it is necessary to use arotatable timing valvedisposed between the stationary spindle and the stationary cylinderblock, which is secured to the spindle. The rotatable valve is driven bythe housingto control the flow of fluid to and from the cylinders. Whenthe hydraulic motor is used as a vehicle wheel drive, it is possible forsolid particles to be mixed with the hydraulic fluid. The system filterwill normally keep the particles from reaching the pump and motor.However, the,

will be broken to permit high pressure fluid deliveredto the motor to beexhausted. This will prevent high pressure fluid from entering thecylinders to cause a hydraulic lockup of the motor.

V 2 the spindle between lands 30 and 32. Fluid communication of therecesses and 28 with each other and with the motor drain cavity isprevented by seals 34.

The spindle 10 has a spline portion 36 on which is splined a cylinderhousing 38 which is secured to the spindle 10 between a shoulder 40 anda locknut 42 which is threaded onto the spindle 10. The cylinder housing38 has formed therein a plurality of cylinder bores 44 which are closedat their radial inner surface by sleeve 46. The sleeve 46 has formedtherein a plurality of oval shaped ports 48 and a plurality of ovalshaped ports 50. The sleeve 46 is positioned in the cylinder housing 38such that one each of the ports 48 and 50 are aligned with each cylinderbore 44. A piston 52 is slidably disposed in each cylinder bore 44 andis adapted for reciprocation therein as will be described later. Eachpiston 52 has a pin and roller assembly 54 operatively connected theretoto provide driving connection between the pistons 52 and a cam 56.

The cam 56 forms a portion of a motor housing, generally designated, 58which also includes a pair of side portions 60 and62. The side portions60 and 62 and It is an object of this invention to provide in animproved radial piston hydraulic motor a drive connection between themotor housing and a distribution valve whereby the distribution valve isnormally rotated with the housing to provide timed fluid flow to andfrom the motor cylinders, and which drive connection will provide anexhaust connection for the high pressure fluid if the valve should beprevented from rotation.

It is another object of this invention to provide in a radial pistonhydraulic motor an improved drive connection between the rotatablehousing and rotatable valve wherein the drive connection. comprises apin adapted to be sheared when the valve is prevented from rotatingsothat a fluid passage is opened through the pin between the highpressure side of the motor and the motor drain passage.

These and other objects and advantages of the present invention will bemore apparent from the following description and drawing in which: i

FIG. 1 is a sectionalelevational view of a hydraulic motor incorporatingthe present invention; and

FIG. 2 is a sectional view taken along 22 of FIG. 1. 6

Referring to the drawings there is shown a hydraulic motor having astationary spindle 10 having formed therein a pair of axial fluidpassages 12 and 14 which are adapted to be connected to a hydraulicpump, not shown. Also formed in spindle 10 is an axial passage 16 whichprovides a drain connection for the fluid motor and is adapted to beconnected to a reservoir not shown. The passage 12 is connected to across passage 18 which is in fluid communication with a recess 20 formedbetween lands 22 and 24 on the spindle 10. A passage 14 is connectedwith a cross passage 26 which is in fluid communication with a recess 28formed on the cam 56 are secured together by a plurality'of threadedfasteners 64 and are aligned relative to each other by dowel pins 66.The camportion 56 has a plurality of cam lobes 68 against which the pinand roller assemblies 54 are in abutting relationship during operationof the fluid motor.

The side portion 60 is rotatably supported on the spindle 10 by atapered roller bearing 70 and is prevented from axial movement on thespindle by a threaded fastener 72 which secures the tapered bearing 70between a washer 74 and a shoulder 76 formed in the side portion 60. Aplurality of fasteners 78 are secured in the side portion 60 and areadapted to permit a drive wheel, not shown, to be secured to the motorhousing 58. The side portion 62 is rotatably supported on the spindle 10by a tapered roller bearing 80 which is located between a shoulder 82 ona spindle mounting member 84 and a shoulder 86 formed in the sideportion 62. The side portion 62 is-also prevented from axial movement bythe threaded fastener 72. The mounting member 84 is used to secure themotor to the machine or vehicle on which it is to be used. An interiorcavity 88 of the motor housing 58 is in fluid communication with thedrain passage 16 through a plurality of passages 90 formed in the sideportion 62 such that fluid leakage past the fluid pistons 52 to thecavity 88 can be returned to the reservoir.

A hub 92 is secured to the side portion 62 and is rotatably separatedfrom the cylinder housing 38 by a roller bearing 94. The hub 92 hasformed therein a recess 96 in which is disposed an enlarged diameter end98 of a pin 100. The pin 100 has a smaller diameter portion 101 pressedinto a valve spool 102 such that the enlarged end 98 abuts the radialface 104 of the valve 102. A blind passage 106 is formed in the pin 100to a depth which will locate the end of the blind passage 106 at adistance spaced outwardly from the face 104 when the pin is pressed inplace.

The valve 102 has formed therein a plurality of oval ports 108 which arein fluid communication with the recess 20 on spindle 10. Also formed inthe valve 102 are a plurality of oval ports 110 which are in fluid communication with the recess 28 on the spindle 10. One of the ports 108,and therefore the recess 20, is in fluid communication with the blindpassage 106 in the pin 3 100. The ports 108 and 110 arecircumferentially separated from each other to provide timed fluid flowto and from the cylinders 44 through ports 48 and 50, when the valve 102is rotated with the motor housing 58.

During the operation of the fluid motor high pressure fluid is deliveredvia passages 12 and 18 to recess 20, while recess 28 and passages 26 and14 are'connected toa fluid reservoir; The high pressure fluid, in recess20, is delivered to the cylinders 44 when the ports 108 are registeredwith the ports 48. Fluid is expelled from the cylinders 44 through theports 50 when they are registered with the ports 1 10. Fluid pressure inthe cylinders 44 cause the pistons 52 to move radially outward such thatthe pin and roller assemblies 54 contact the cam lobes 68 to cause themotor housing 58 to rotate in the direction of arrow A. When the rollers54 have reached the radial outermost point of cam 68, continued rotationof the motor housing 58 forces the rollers 54 and pistons 52 inwardly toexpell fluid from the cylinders 44 through ports 50 and 110. When fluidpressure is not admitted to the motor, a pair of garter springs 112acting on the pin and roller assemblies 54 urge all of the pistons 52radially inwardly to prevent contact between the cam 56 and the rollerand pin assemblies 54. Under this condition the motor housing 58 is freeto rotate without the generation of pumping losses within the motor.

If the valve 102 should become seized with the spindle or the sleeve 46,such that rotation of the valve 102 is retarded or prevented, the pin100 will shear at the face 104. When the pin has sheared the highpressure side of the motor, recess 20 will be in fluid communicationwith the cavity 88, and therefore drain passage 16, to preventpressurization of the cylinders 44. If excess fluid is being deliveredto the motor at the time of the valve seizure, the pressure in cavity 88will increase due to the restricted nature of the drain passage 16, suchthat the increased pressure in cavity 88 will balance any fluid pressureon the pistons 52 so that the springs 112 will move the pistons inwardlythereby permitting free rotation of the housing 58.

From the above description it can be seen that hydraulic lock conditionsin the cylinders 44 is prevented when the valve 102 is prevented fromrotating. Thus, if the motor is used, for example, as an auxiliaryvehicle drive, the wheel could continue to rotate even through the motorbecomes inoperative.

Obviously, many modifications and variations of the present inventionare possible in light of theabove teachings. It is, therefore, to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

What is claimed is: l. A hydraulic motor comprising a spindle; a statorsecured to said spindle and having a plurality of radially extendingcylinder bores; port means secured to said stator for directinghydraulic fluid to and from said cylinder bores; passage means in saidspindle for directing hydraulic fluid to and from said motor; pistonmeans reciprocably disposed in said cylinder bores including rollermeans at the radially outer ends thereof; rotatablehousing meansrotatably supported on said spindle and surrounding said stator andpistons and including an interin cavity and a cam portion adapted to bedriven by said roller means upon reciprocation of said piston means;valve means'rotatably disposed between said port means and said spindlefor directing timed hydraulic fluid interchange between said cylinderbores and said passage means; and drive connecting means drivinglyconnected between said valve means and said rotatable housing means fornormally maintaining a timed relationship therebetween and includingcentral passage means for permitting hydraulic fluid communicationbetween said passage means directing hydraulic fluid to said motor andsaid interior cavity when said drive connecting means is brokenand; forpreventing hydraulic locking of said piston means in said cylinderbores.

2. A hydraulic motor comprising a spindle; a stator secured to saidspindle and having a plurality of radially extending cylinder bores;sleeve means secured to said stator having a plurality of cylinder portstherein for directing hydraulic fluid to and from said cylinder bores;

passage means in said spindle for directing hydraulic fluid to and fromsaid motor; piston means reciprocably disposed in said cylinder boresincluding roller means at the radially outer ends thereof; rotatablehousing means rotatably supported on said spindle and surrounding saidstator and pistons and including an interior cavity and a cam portionadapted to be driven by said roller. means upon reciprocation of saidpiston means; valve means rotatably disposed between said sleeve meansand said spindle and including a plurality of supply and exhaust portsfor directing timed hydraulic fluid interchange between said cylinderports and said passage means; and drive connecting means drivinglyconnected between said valve means and said rotatable housing means fornormally maintaining a timed relationship therebetween and including pinmeans secured in said valve means having a portion drivingly connectedwith said rotatable housing means and a blind passage centrally locatedin said pin open at one end to one of said supply ports and closed atthe other end to normally prevent fluid flow therethrough, said pinbeing shearable between the ends of said blind passage for providingfluid communication between said one supply port and said interiorcavity when said valve means is prevented from rotating with saidrotatable housing means.

1. A hydraulic motor comprising a spindle; a stator secured to saidspindle and having a plurality of radially extending cylinder bores;port means secured to said stator for directing hydraulic fluid to andfrom said cylinder bores; passage means in said spindle for directinghydraulic fluid to and from said motor; piston means reciprocablydisposed in said cylinder bores including roller means at the radiallyouter ends thereof; rotatable housing means rotatably supported on saidspindle and surrounding said stator and pistons and including an interincavity and a cam portion adapted to be driven by said roller means uponreciprocation of said piston means; valve means rotatably disposedbetween said port means and said spindle for directing timed hydraulicfluid interchange between said cylinder bores and said passage means;and drive connecting means drivingly connected between said valve meansand said rotatable housing means for normally maintaining a timedrelationship therebetween and including central passage means forpermitting hydraulic fluid communication between said passage meansdirecting hydraulic fluid to said motor and said interior cavity whensaid drive connecting means is broken and; for preventing hydrauliclocking of said piston means in said cylinder bores.
 2. A hydraulicmotor comprising a spindle; a stator secured to said spindle and hAvinga plurality of radially extending cylinder bores; sleeve means securedto said stator having a plurality of cylinder ports therein fordirecting hydraulic fluid to and from said cylinder bores; passage meansin said spindle for directing hydraulic fluid to and from said motor;piston means reciprocably disposed in said cylinder bores includingroller means at the radially outer ends thereof; rotatable housing meansrotatably supported on said spindle and surrounding said stator andpistons and including an interior cavity and a cam portion adapted to bedriven by said roller means upon reciprocation of said piston means;valve means rotatably disposed between said sleeve means and saidspindle and including a plurality of supply and exhaust ports fordirecting timed hydraulic fluid interchange between said cylinder portsand said passage means; and drive connecting means drivingly connectedbetween said valve means and said rotatable housing means for normallymaintaining a timed relationship therebetween and including pin meanssecured in said valve means having a portion drivingly connected withsaid rotatable housing means and a blind passage centrally located insaid pin open at one end to one of said supply ports and closed at theother end to normally prevent fluid flow therethrough, said pin beingshearable between the ends of said blind passage for providing fluidcommunication between said one supply port and said interior cavity whensaid valve means is prevented from rotating with said rotatable housingmeans.